Hi,
Almost 12 yrs ago when we got our puppy Molly, my wife and I were at our wits end about housetraining! After 3 months, we finally said that if she goes in the house one more time, then.....not know what to do with her. All of a sudden, she started going to the back door, wanting out!
We picked her up every time we thought she wanted to go, sat her down by the back door, waited a minute, then let her outside. Eventually, it paid off.
I think persistence is a key word here.
Here is a link with some good tips and suggestions:
http://www.hilltopanimalhospital.com/housebreak2.htm
Look under "Steps in Housebreaking Puppies"
I do wish you and he the very best. I am not a Vet, but just a dog lover for over 50 yrs.